Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred tax benefit recognized in OCI	$ 400,000	$ 400,000	$ 300,000	$ 0
Effective tax rate		16.90%	49.00%	38.20%
Change in enacted tax rate, percent		14.00%
Income tax benefit, enacted U.S. Tax Reform	24,500,000
Current tax expense, transition tax		$ 0
Provision (benefit) for income taxes		29,600,000	$ 42,600,000	$ 52,200,000
Net operation loss, foreign	27,700,000	27,700,000
Net operation loss foreign expected to expire	6,000,000	6,000,000
Net operation loss foreign with no expiration date	21,700,000	21,700,000
Unrecognized tax benefits, penalties and interest		500,000	1,000,000	1,200,000
Positive undistributed earnings to be reinvested (less than)	$ 1,000,000	1,000,000
Reduction from lapse of statute of limitation		$ 400,000	$ 0	$ 100,000
Minimum
Operating Loss Carryforwards [Line Items]
Foreign net operation loss carryforwards, expiration period (in years)		3 years
Maximum
Operating Loss Carryforwards [Line Items]
Foreign net operation loss carryforwards, expiration period (in years)		10 years